In a liquid crystal display device, power consumption caused by load of a display panel is one of the major parts of the total power consumption of the display panel. The power consumption caused by the load of the display panel is associated with a power supply voltage for driving the display panel, and when the load of the display panel is fixed, the higher the power supply voltage for driving the display panel is, the larger power consumption the load of the display panel will cause Generally, in the liquid crystal display device, for better contrast and quicker response, value of the power supply voltage for driving the display panel may be increased as much as possible.
However, when the display panel is not required to have a high contrast and a quick response (for example, when a static image or paperwork is displayed), a lower power supply voltage may be used for the display panel so as to lower the power consumption. In addition, when a mobile device in use goes into an energy-saving mode, a lower power supply voltage may also be used for the display panel so as to lower the power consumption.
Therefore, it is required to provide a device and a method for adjusting a supply power for a display panel, so as to lower the supply power for driving the display panel when necessary.